1.16.1.1 rgbcolor variable

Most plot commands assign a single color (linetype) to each element of the
plot. If there are multiple plots on a single graph, the default color
(linetype) is incremented sequentially. You can instead assign a separate
color for each data point, line segment, or label based on additional
information in the input data file. This is indicated by the colorspec
keyword ‘variable‘.

‘lc rgbcolor variable‘ tells the program to use a 24-bit RGB color from a
separate column in the data file. This requires a corresponding additional
column in the using specifier. The extra column is interpreted as a 24-bit
packed RGB triple. These are most easily specified as hexidecimal values
(see ‘rgbcolor‘). Text colors are similarly set using ‘tc rgbcolor variable‘.